Desalination Process Research Articles

Towards a more sustainable hydrogen energy production: evaluating the use of different sources of water for chloralkaline electrolyzers

Water scarcity is becoming a serious threat for the implementation of energy storage devices based on hydrogen in the inland of dry regions, because of the difficulties in finding appropriate sources of water and the important environmental problem associated with the discharge of rejection saline streams produced during the purification of water. This becomes an opportunity for chloralkaline technology in which the quality of water used is lower than the required in other hydrogen production technologies. This work compares the performance of chloralkaline electrolyzers fed with different solutions of NaCl (from brackish water to brines) with that obtained feeding two natural water samples (seawater and porewater) and three processed waters (rejections streams of the electrodialysis, reverse osmosis of the porewater and a real rejection of the reverse osmosis of a vineyard). All tests were made with a lab-scale 3-D printed cell where, in addition, the performance of Ti/RuO2 and Pb/PbO2 anodes were compared, being always better the results obtained in the tests made with the Ti/RuO2 electrode. Results obtained indicate that efficiencies reached using these alternative sources are lower than those which can be reached using synthetic brines that, in turn, were very near to the standards reached in the chloralkaline industry. In the case of hydrogen production, the maximum values were obtained for seawater, reaching efficiencies proximate to 8.0 mg H2 (Wh)-1. Rejection streams of desalination processes were found to be less efficient, attaining values in the range 2 and 4 mg H2 (Wh)-1. Regarding the production of chlorine and caustic soda, better performances were reached again with seawater (161.7 mg Cl2 (Wh)-1 and 0.092 mg OH- (Wh)-1 ) and with the rejection of the electrodialysis, which also reached sound values of 90.4 mg Cl2 (Wh)-1 and 0.107 mg OH- (Wh)-1. Results obtained are promising and indicate a path that must be further worked for the implementation of a greener water management strategy in the hydrogen -based energy storage technology.

Challenges of forward osmosis desalination processes using hydrogels as draw agents

The present study aims to investigate the properties, identification, and comprehension of the obstacles encountered in the forward osmosis process when utilizing a hydrogel drawing agent (FO-HG). Furthermore, a comparison is made between the FO-HG system and conventional forward osmosis systems employing a salt solution drawing agent. The comparison and evaluation of the swelling process of hydrogel and the kinetics of water penetration are conducted in both un-constrained and constrained states. Furthermore, the investigation and analysis are carried out to determine the presence or absence of internal concentration polarization (ICP) and external concentration polarization (ECP) phenomena. These phenomena are studied in situations with and without mixing, as well as in different orientations of the membrane (FO-mode and PRO-mode). The impact of these phenomena on the water flux of the systems FO-HG and FO-NaCl is also examined. An evaluation is conducted to determine the influence of the amount and size of hydrogel used as a draw agent in the FO-HG system on the water flux. The results of the study reveal that smaller hydrogel particles in the FO-HG system exhibit a higher flux compared to larger particles. Additionally, it is observed that the water flux in PRO-mode is unexpectedly higher when salt water is used as feed solution. This phenomenon can be ascribed to a counter-osmotic effect, originating from the FO state. Despite the high water absorption capacity of hydrogel and its potential as an ideal drawing agent in the forward osmosis process, the results demonstrate that the flux of the FO-HG system is inferior to that of the FO-NaCl system. Finally, the focus is on resolving the low flux issue by suggesting a process involving multiple cycles throughout day and night. We investigate the influence of hydrogel particle size, membrane surface, hydrogel layer thickness, as well as swelling and deswelling time in one cycle. The swelling time displays a peak at an optimal absorption duration, while the deswelling time does not show a similar optimal point, highlighting the difference between swelling and deswelling phenomena. Therefore, the hydrogels' high absorption capacity alone is insufficient for achieving desalination success. The research findings emphasize the high importance of synthesis of a membrane with minimal resistance, enabling a high water flux and suitable selectivity.

Hierarchical Ti3C2Tx MXene@Honeycomb nanocomposite with high energy efficiency for solar water desalination

The utilization of solar-driven interfacial evaporation holds immense promise in enhancing energy efficiency and establishing sustainable methods for seawater desalination and water purification. While designing the materials to achieve high evaporation efficiency, the tuning of materials with porosity and surface chemistry is very crucial. Novel sustainable materials are of great importance for solar water desalination applications since clean water production is utmost important in the current era. There exists a lack of exploration in modifying the surface wettability states of solar evaporators to expedite the vapor generation rates. In this study, we showcase a hydrophilic Ti3C2Tx MXene-coated carbonized honeycomb (CHC) (Ti3C2Tx MXene@CHC) nanocomposite-based hexagonal-shaped evaporator surface. This is the first-time report on the effective utilization of hierarchical CHC for the preparation of solar absorber comprising of Ti3C2Tx MXene@CHC nanocomposite, particularly for the solar water desalination. The Ti3C2Tx MXene@CHC nanocomposite evaporator achieves an impressive water evaporation rate of 1.6 kg m−2 h−1 with 90% efficiency under 1 sun illumination. The augmented thickness of the water layer in the hydrophilic surface of the Ti3C2Tx MXene@CHC nanocomposite helps in facilitating the rapid escape of water molecules. The relatively elongated contact lines in the hydrophobic region simultaneously ensure substantial water evaporation, significantly enhancing the water desalination process. The Ti3C2Tx MXene@CHC nanocomposite exceeds stringent quality benchmarks, signaling its potential for solar water desalination.

Review on advanced techniques in zero liquid discharge water desalination via humidification-dehumidification within thermally-driven transport reactors

The article examines an advanced zero liquid discharge (ZLD) desalination method focusing on humidification-dehumidification (HDH) in thermally driven transport reactors. The limited availability of water, particularly in dry locations, has prompted the advancement of several desalination techniques. Reverse Osmosis (RO) is a prevalent membrane technology in the market; however, it has restrictions regarding brine disposal. ZLD technologies strive to mitigate environmental consequences by transforming saltwater into drinkable water and precious salts while minimizing waste. Membrane Distillation and Crystallization (MD-C) is notable as a highly efficient Zero Liquid Discharge (ZLD) technique. Despite its high energy consumption, it can combine MD-C with renewable or waste energy sources to improve sustainability. Freeze Desalination (FD) was reviewed for its economic efficiency, especially when utilizing cold energy from liquefied natural gas (LNG). Hybrid systems that combine Forward Osmosis (FO) and membrane distillation with condensation (MD-C) can potentially improve water recovery and decrease energy usage. The HDH desalination process imitates the natural precipitation process, examines its ability to operate at low temperatures, and highlights its potential for integration with renewable energy sources. The review discusses the HDH design, the effect of salinity on its performance, and the different dehumidification technologies. It emphasizes the significance of creative methods in achieving sustainable water management.

Kinetic study on cyclopentane hydrates in the presence of sodium chloride

Water is an important resource for human life. The lack of clean water in the world now becomes more serious. As a result, seawater desalination to produce fresh water is becoming indispensable. In recent years, hydrate-based desalination is a potential solution for the drinking water shortage issue. Recently, Cyclopentane (CP) is used as a hydrate former for desalination process via crystallization at low temperature and atmospheric pressure. The objective of this study is to provide the new kinetic data of CP hydrates in the presence of sodium chloride with a concentration of 3.5 wt.%. The experimental data for CP hydrates in the presence of sodium chloride are obtained in a batch reactor system with a setup temperature range of -2.5 to -0.5 oC and at atmospheric pressure. The effects of temperature, agitation speed and amount of CP on kinetics of CP hydrate formation are also performed.

Renewable energy-driven for sustainable off-grid desalination: A comprehensive review on technical highlights and process

Despite the traditional desalination processes have achieved tremendous progress in terms of technology and cost, it is still limited by the high energy consumption and carbon emissions brought about by expensive fossil fuels. Finding alternative energy sources is essential to meet the growing demand for desalination. Over the past few decades, plenty of efforts have focused on driving the desalination process through renewable energy sources in order to achieve the goal of environmentally friendly off-grid desalination and zero liquid discharge. However, limited by technology and economic cost, the desalination processes driven by renewable energy are difficult to carry out large-scale application, and they are more used as an auxiliary unit of the traditional desalination processes. First of all, this article reviews the basic principles of solar interface evaporation technology, and further, summarizes the sustainable desalination technologies driven by solar and geothermal energy completely. In the end, the current global environment and energy troubles are discussed, and the necessity and significance of promoting renewable energy for desalination in the future are emphasized. This review will assist to promote attention to the development and utilization of renewable energy sources, with a focus on large-scale renewable-driven off-grid desalination projects in the future.

Flat plate solar collector activated with alumina-silicon dioxide-copper oxide hybrid nanofluid: Thermal performance study

Flat plate collectors (FPC) play a crucial role in solar-powered desalination by harnessing sunlight to purify water. They are acclaimed for their simple yet efficient design, as their dark, flat surfaces effectively transfer heat to the desalination system, making them a preferred choice for sustainable water treatment. Nevertheless, the performance of FPC systems is hindered by the working fluid, which reduces the productivity of distilled water, particularly without the use of nanotechnology to enhance the fluid’s thermal properties. This study aims to enhance the performance of FPCs in desalination processes by integrating them with conventional still systems and employing hybrid nanofluids. These nanofluids, composed of alumina (Al2O3), silicon dioxide (SiO2), and copper oxide (CuO) nanoparticles at concentrations of 0.3 % in 50:50 combinations, namely Al2O3/SiO2, SiO2/CuO, and Al2O3/CuO, are introduced into the working fluid (water). The integration of these hybrid nanofluids is evaluated in terms of thermal behaviour, including thermal conductivity, outlet temperature, energy gain, water productivity, and thermal and exergy efficiency of FPC. Among the different combinations, the Al2O3/CuO hybrid nanofluid demonstrates the highest thermal conductivity, outlet temperature, energy gain, water productivity, as well as thermal and exergy efficiencies, reaching approximately 0.631 W/mK, 87.5 °C, 568.7 W, 124.3 ml/m2, 61.4 %, and 6.7 %, respectively. The Al2O3/CuO featured flat plate solar collector system has the potential for an optimum system of addressing the pressing global issue of water scarcity.

Assessment of salt-free electrodialysis metathesis: A novel process for brine management in brackish water desalination using monovalent selective ion exchange membranes

Since reverse osmosis (RO) is often limited to a water recovery of 70–85 %, implementing a secondary process like electrodialysis metathesis (EDM) to treat concentrate can increase system water recovery. This study explores salt-free electrodialysis metathesis (SF-EDM) as an alternative to conventional EDM to investigate its performance in the zero discharge desalination (ZDD) process. SF-EDM utilizes monovalent-selective ion exchange membranes, eliminating the need for sodium chloride (NaCl) as a substitution solution. This approach generates one diluate stream and two highly soluble concentrate streams enriched in calcium and sulfate, respectively. In this article, a series of lab-scale tests based on synthetic and real RO concentrate were performed to investigate how SF-EDM performs operating at high water recovery with a feedwater with high scaling potential. We critically analyze the performance in terms of salinity reduction, selectivity, and energy consumption. Results of the study show that without the addition of NaCl, the process was able to selectively separate sulfate and calcium into two concentrate streams achieve a salinity reduction of 93 % and a total system water recovery (RO and SF-EDM) of 90 %. A technoeconomic analysis found SF-EDM to be 80 % of the cost of conventional EDM making it a competitive technology for brackish water RO concentrate management.

Microstructural design of crown nanopores in graphene membrane for efficient desalination process

Designing a membrane with simultaneous high water permeability and desalination rate to overcome the trade-off presents a persistent and substantial challenge. In this paper, we employed molecular dynamics simulations to design the structure of the graphene crown ether reverse osmosis membrane and elucidate the relationship between the membrane's microscopic separation mechanism and its structure-activity.The results show that the water permeability through crown graphene nanopores exceeded that of the original graphene nanopores by an order of magnitude, and hundreds of times greater than that of the traditional reverse osmosis membrane. Additionally, the water permeation in multilayer crown graphene nanopores also surpassed that in monolayer original graphene nanopores. The water permeability exceeds 46.73 L/cm2/day/Mpa with 100 % salt rejection. Furthermore, the various sizes and shapes of graphene nanopores significantly influence water permeation. Within crown graphene nanopores, a narrow pore enables superior water permeation and salt rejection compared to a circular shape, unlike original graphene nanopores. Observed from MD simulation trajectories,this highly water permeation is caused by the hydrogen bonding between crown ether graphene and water molecules. First-principle calculations further confirm that water transport in graphene crown ether is energetically more favorable than in original graphene nanopores. Our findings support crown graphene membranes as promising candidates for seawater desalination.

Reverse Osmosis Concentrated Water Treatment Technology Research

With the national “double carbon” goal, energy saving and consumption reduction strategic plan to promote, more and more enterprises will be “zero discharge” of wastewater as the ultimate goal of industrial wastewater. Reverse osmosis (RO) process is the most common way of water treatment process, in the treatment of water treatment and pure water preparation at the same time, will be accompanied by a variety of inorganic and organic pollutants contained in the by-products of concentrated water, these difficult to deal with high salt, complex composition of the reverse osmosis concentration of water, not directly discharged without treatment, not only to make a lot of water in the concentration of water to be a waste of water resources, will be a large extent on the ocean, soil and other natural environments to cause irreversible damage. Reversible damage to the ocean, soil and other natural environments. Therefore, it is of great significance to protect the environment by finding an economical and efficient treatment method for RO concentrated water. For the regeneration of fresh water resources of RO concentrated water, there have been many international reports on the development of zero liquid discharge (ZLD) or near-zero liquid discharge technology, through the membrane technology to reverse osmosis concentrated water concentration, water recycling, reduce the volume of concentrated water, and then based on the thermal technology of concentrated water desalination, evaporation and crystallization process leads to the recovery of water, and at the same time, the process of solid by-products after dehydration, purification, can also produce a considerable amount of water. At the same time, the solid by-products produced in the process can be dehydrated and purified, which can also produce considerable economic value of commodities. Concentrated water concentration process around how to achieve low-cost RO concentrated water concentration process, in the disc tube reverse osmosis (DTRO), electrodialysis (ED), membrane distillation (MD) and forward osmosis (FO) and other new membrane concentration technology field carried out a wide range of research on the concentration of further concentrated water to provide more prospects for application. Solidification crystallization through reasonable crystallization control and solid-liquid separation technology, can achieve effective separation and purification of solutes, for various industries to provide solid products in line with the quality requirements, commonly used evaporation crystallization, cooling crystallization, solvent crystallization, ion exchange methods and other ways. Through the study of reverse osmosis concentrated water concentration treatment, crystallization and solidification of the two important links of the production process plan, summarize the practicality of various technologies and advantages and disadvantages, integration of existing technologies, research suitable for reverse osmosis concentrated water resources utilization of economic technology solutions, optimize the treatment process, and ultimately realize the application of engineering examples, is the direction of the efforts of researchers in recent years.

Investigating different scenarios of integrating solar-assisted carbon capture with combined cycle power plant and water desalination system

In this work, an optimal algorithm-based integration of solar thermal energy with carbon capture and desalination processes were proposed. The stripper columns, identified as the most energy-consuming equipment, were designed with constant capacities to ensure practicality and applicability. Results show that, without affecting the power plant's efficiency, using a solvent tank as an energy storage system (scenario-2) increases total CO2 capture from 45 % to 98 % compared to a part-time solar power system (scenario-1). Utilizing two solvent tanks reduces waste energy from 87 % to 67 % (scenario-3), while achieving 100 % CO2 capture. Using three different stripper columns (scenario-4) lowers the levelized cost of energy by 20 %. Incorporating an additional multiple effect distillation system (scenario-5) reduces levelized cost of energy and energy loss by 26 % and 74 %, respectively. Approximately 28 % of the total solar energy collected (4.64 × 106 MWh) was used to capture 1.57 × 106 ton.year−1 of CO2. The remaining energy was used in desalination to produce 9.4 × 106 m³.year−1 of fresh water, increasing overall energy efficiency from 28 % to 81 %, and reducing waste energy to 0.88 × 106 MWh, just 26 % of previous scenarios' waste.

Hydrodynamic solar-driven interfacial evaporation - Gone with the flow

Evaporation has been one of the most classic desalination processes on the Earth. When we try to use the power of water flow itself, the evaporation process can perform even better. Here, we report a hydrodynamic solar-driven interfacial evaporation process which water evaporation rate can achieve 6.58 kg·m-2·h-1 (over 100 times higher than natural evaporation). A waterwheel-structure solar interfacial evaporator was designed and assembled by printed filter papers. The evaporator can both rapidly distribute solution on the evaporation interface and be hydraulically driven to rotate continuously to improve the evaporation rate by water flow. The hydrodynamic solar-driven interfacial evaporation process successfully overcomes the problem of slow diffusion of water vapor, but also realizes the day-and-night operation of process and the self-cleaning of salt fouling. Apart from the application in solar desalination, the developed evaporator has great potentials in vapor production and salt recovery for industrial use.

Improvement of low-cost solar-powered desalination technologies in low-light intensity

Enhancing the efficiency of low-cost solar-powered desalination technologies, such as solar stills (SS), is essential for ensuring continuous access to freshwater in remote, water-stressed areas, particularly during cloudy or rainy days when the performance of conventional SS systems is compromised. This study introduces an innovative stepped solar still design, optimized for ease of operation, maintenance, environmental compatibility, and improved efficiency, especially under low-light conditions. The impact of the inlet mass flow rate on the desalination process was investigated to enhance distilled water production. Light absorption and step hot spot temperatures were further improved by incorporating natural and cost-effective absorbers, such as carbon, and an innovative soil-carbon combination. The synergy of this soil-carbon combination, enhancing light absorption, heat transfer, and storage through increased surface contact during radiation exposure and its distribution during shutdown, led to a 12.8% and 3% increase in distilled water production over the 4-hour test duration, compared to the baseline and carbon-only tests, respectively. This innovative design, combined with the use of a soil and carbon mixture, significantly improves the performance of solar distillation systems. These findings contribute to the development of sustainable, low-cost, and energy-efficient solutions for freshwater provision in remote areas, addressing both water scarcity and energy conservation challenges.

Triple strategies for process salt reduction in industrial wastewater treatment: The case of coking wastewater

Human activities introduce nutrient elements into wastewater, yet the saline byproducts from treatment are poorly managed. Selecting a low-salt process, without compromising treatment efficacy, is essential for reaching the zero-discharge goal in water treatment. Based on the engineering treatment process of coking wastewater, the source and reduction strategy of salts were studied. The results showed that 73.21 % of the residual salt originated from raw coal, 10.87 % from raw water, and 15.92 % from chemicals, respectively. Triple strategies for process salt reduction (PSR): load salt reduction, technology salt reduction and cyclic salt reduction can bring 0.411 mS/cm·m3, 0.217 mS/cm·m3 and −0.070 mS/cm·m3 salt reduction, and also bring 1.455 CNY/m3, 0.836 CNY/m3 and 0.360 CNY/m3 net present value, respectively. Meanwhile, PSR is also a low-carbon strategy, which will bring about carbon emission reduction of 1.6948 kg CO2-eq/m3, 0.4898 kg CO2-eq/m3 and 1.4082 kg CO2-eq/m3 respectively. The Resource/Carbon source Management-Oxic − Hydrolytic & Denitrification − Oxic (A-OHO) process, incorporating PSR, cuts costs by 27.83–31.66 % and carbon emissions by 18.68–19.54 % compared to conventional wastewater treatment methods. It can be predicted that the PSR in the standard treatment stage can provide a guarantee for the subsequent water reuse and desalination process to reduce project investment and operating costs, and at the same time benefit the macro environment from the aspects of carbon emission reduction and sludge reduction.

Optimising the effectiveness of osmotic desalination process by using graphene-based nanomaterials

This work examines how graphene-based nanoparticles can be integrated into membranes to improve the effectiveness of water treatment in osmotic desalination processes. This is important since sustainable practices can help address the world's water scarcity. Water treatment, desalination, and resource recovery are areas where osmotic desalination shows great potential. However, membrane performance constraints frequently impede its efficacy. High mechanical strength, superior hydrophilicity, and the ability to lessen internal concentration polarisation are just a few of the remarkable qualities that make graphene-based nanoparticles stand out. In order to increase the membranes' overall functionality, these nanoparticles were created and added to them. Comparing the study to conventional membranes, the main goals were to increase water flux rates and salt ion rejection capacities. It was shown by experimental results that the membranes strengthened with graphene-based nanoparticles performed better. They outperformed conventional membranes in terms of water flow growth and salt ion rejection rates improvement. In order to advance osmotic desalination technologies towards more effective and sustainable water treatment options, this study highlights the revolutionary potential of graphene-based nanoparticles. Graphene-based nanoparticles provide an attractive option for tackling major water issues worldwide by improving membrane characteristics that are essential for osmotic desalination, such as permeability and selectivity. Water management techniques that are environmentally sustainable are supported by their integration into membranes, which also enhances performance metrics. This study opens the door for creative approaches to resource recovery and water treatment by providing important insights into the creation of cutting-edge materials specifically designed for osmotic desalination applications.

Transport numbers of ion-exchange membranes in ternary mixtures of KCl, H2O and ethanol relevant for electrodialysis and desalination processes

Understanding the transport phenomena in electrolyte mixtures involved in electrochemical processes is of utmost importance for the modelling and improvement of battery technology, fuel cells, ion-exchange membrane processes, and much more. In this work, we derive relations and present methods for the analysis of electric potential measurements of concentration cells and ion-exchange membrane permselectivity with ternary mixtures of KCl, H2O and ethanol (EtOH). Measurements of electric potentials across the Selemion CMVN (cation-exchange) and AMVN (anion-exchange) membranes in this ternary mixture suggest that the presence of EtOH affects the membrane permselectivity, but that the transference of EtOH is zero; i.e., ta=0. Instead, the decrease in membrane permselectivity can be explained by a varying water transference coefficient, tw. In the absence of EtOH we find tw≈4 in both membranes, and that the decrease in tw is proportional to the average thermodynamic activity of EtOH in mixtures adjacent to the membranes. The membranes were also found to be charge selective, as quantified by the ionic transport numbers; i.e., tK+=1 for the Selemion CMVN and tK+=0 for the Selemion AMVN. The presented method can readily be extended and leveraged to determine transference coefficients in other electrochemical systems.

Multi-variable fuzzy adaptive time-varying sliding mode control (MVFATVSMC) of the reverse osmosis-photovoltaic desalination system

Among the different desalination systems, reverse osmosis is popular due to its specific characteristics. Two challenges in these systems are power supply and compensation for the imposed disturbances and uncertainties which affect the performance of the system. To study these two challenges all main subsystems of the photovoltaic-reverse osmosis (PV-RO) system are considered. A photovoltaic system is considered for power supply and robust controllers are proposed to deal with the uncertainties and disturbances. For these purposes, all parts of the PV-RO desalination process are considered. Maximum power is tracked in different sun radiations and temperatures using a Mamdani-type fuzzy controller optimized by the invasive weed algorithm (IWA). This new MPPT controller gets about 10 % more power, 60 % lesser fluctuations, and 20 % smaller rise time. The speed controller of the induction motor and the pressure controller are fuzzy-PID. An adaptive time-varying sliding mode control (ATVSMC) is proposed to control the RO system because this system is highly nonlinear with many uncertainties and disturbances. The controller has global robustness and regulates the system to the desired points at a specified time. In this controller, knowing the maximum limit of the system uncertainties is not essential, which is a practical advantage for the PV-RO system. The numerical simulations in different scenarios and a comparison to existing work show the superiority of the proposed controllers. This novel controller decreases the overshoot and settling time of the bypass stream velocity by about 3.5 % and 7.6 % in comparison to super-twisting sliding mode control (STSMC), respectively. The settling time of the retentate stream velocity has decreased by about 9 %. Moreover, there are no fluctuations in the control inputs and outputs, and the amplitude of the bypass stream control input has decreased by about 98 %.

Development and modeling of power, hydrogen and freshwater production based on a novel double-flash geothermal power plant

In this article, a novel geothermal energy-assisted multigeneration plant is proposed and analyzed from the thermodynamic, economic, and environmental perspectives. In the design of the geothermal power system, a transcritical Rankine cycle, which employs CO2 as the working fluid (tCO2-RC), a Kalina cycle (KC), a hydrogen generation sub-plant, and a desalination unit are considered. The reverse osmosis (RO) desalination process is used for freshwater production, while the proton exchanger membrane (PEM) electrolyzer is utilized for hydrogen generation. In addition, parametric analyses are conducted to ascertain the impacts of the temperature of the geothermal source, mass flow rate, and flash chamber pressure on system performance. According to the results, the plant's overall energetic and exergetic efficiencies are determined to be 8.6 % and 34.9 %, respectively where the net power production is calculated as 3317.94 kW, and the system's total irreversibility is found to be 5852.88 kW. Furthermore, the hourly H2, O2, and freshwater generation amounts are 8.5 kg, 49.1 kg, and 9.3 m3, respectively. Finally, the levelized energy cost (LEC) and sustainability index of the system are found to be 0.128 USD/kWh and 0.215.

A novel solar-driven vacuum desalination unit: Simultaneously venturi-induced self-evaporation and self-condensation with fresh water cycle

Integrating solar energy in desalination processes offers a cost-effective and efficient solution. Moreover, reducing the saturated temperature of water vapor through pressure reduction can lower energy consumption and improve evaporation rates. This study investigates the performance of a novel venturi system integrated with an evacuated tube collector (ETC) that simultaneously conducts low-pressure evaporation and condensation. The research evaluates the system’s response to variations in flow rate and explores the potential for reducing freshwater pump activity to conserve energy. Increasing the flow rate led to a greater pressure differential across the venturi, causing a decrease in throat pressure. The system achieves its peak water production at a flow rate of 75 L per minute (LPM), yielding 9.02 kg/m2 with a system pressure of 0.297 bar. This production signifies a notable surge of 37.01 % compared to the recorded minimum flow rate. The cost analysis indicates that the cost of producing one kilogram of water per unit area is $0.045. The system achieved its maximum efficiency of 40.87 % by decreasing the water pump operation time to 1.5 h/day while following a cycling pattern of 5 min on-15 min off.

Ab Initio Simulation of Liquid Water without Artificial High Temperature.

Comprehending the structure and dynamics of water is crucial in various fields, such as water desalination, ion separation, electrocatalysis, and biochemical processes. While reported works show that the ab initio molecular dynamics (AIMD) can accurately portray water's structure, the artificial high temperature (AHT) from 120 to 30 K is needed to mimic the quantum nature of hydrogen-bond network from GGA, metaGGA to hybrid functionals. The AHT proves to be an inadequate approach for systems involving aqueous multiphase mixtures, such as water-solid interfaces and aqueous solutions. This is due to the activation of additional phonons in other phases, which can lead to an overestimation of the dynamics of nearby water molecules. In this work, we find that the regularized SCAN (rSCAN) functional effectively captures both the structure and dynamics of liquid water at ambient conditions without AHT. Moreover, rSCAN closely matches experimental results for the hydration structures of alkali, alkali earth, and halide ions. We anticipate that the versatile and accurate rSCAN functional will emerge as a key tool based on ab initio simulation for investigating chemical processes in aqueous environments.